One of he big problems in NYC is that a huge number of people live in high rise buildings where elevators are the only practical way for residents to get to and from their apartments. Also (somebody expert in architecture for such buildings please correct me if I’m wrong) it appears they wold need electric pumps to get water to the higher floors. A lot could be done for such buildings’ residents if the city just moved generators from building to building, providing power to run such services.
In the case of tall buildings, typically taller than 10 stories, you are exactly correct. Municipal water pressure can never push/lift water higher than that with meaningful pressure. Tall buildings not only have to be built with booster pumps on subsequently higher floors but they must have backup power to run them. These are not only “good sense” rules but are fire code rules to make sure a fire can be fought internally. What’s cute, and it’s not a rule, is that most of these tall places get built with the generators IN THE BASEMENT which is just where they need to be in a FLOOD. Who would EVER guess that a basement might flood on a friggen island that is built on sand that has a natural water table about 10 feet below surface?
I don't understand the water shortage for the rest, it's not like the whole country is down, a dozen or so miles inland there is plenty of water and upstate NY has loads of swimming pool tankers to fill up, also diesel is available to fuel the trucks to bring it in.
Of course if they must have Aquafina in eco-bottles then yes, there may be shortages.